The development of technology in the twentieth century allows biomedical devices to be used widely in many different parts of the body for applications such as orthopaedic implants, pacemakers, cardiovascular stents, neural prosthetics and drug delivery systems. For example, between 1990 and 2000, the number of total hip replacements operation increased by 33%; this number is estimated to increase by up to 50% between 2000 and 2030. Over the past two decades, coronary stents have become a new standard in angioplasty procedure. Sustained intraocular drug release with implantable devices has been used to treat vitreoretinal diseases. Often, complications arise from these biomedical devices due to inflammation and/or foreign body reaction. Inflammation is caused by the implant's inability to resist bacteria adhesion. Foreign body reaction occurs when the implant is encapsulated with a dense collagen capsule. Direct medical costs associated with bacterial infections exceed $3 billion annually in the U.S. alone. To minimize bacteria adhesion and foreign body reaction, an anti-fouling material is often coated onto biomedical devices before their implantation.
Polyethylene glycol (PEG) and poly (2-hydroxyethyl methacrylate) (PHEMA) hydrogel are commonly used anti-fouling material in contact lenses, tissue scaffolds, drug delivery carriers and medical implants. Despite the low cost of PEG, long-term application of PEG may cause the device to oxidize, eventually destroying its hydrophilic properties and limiting long-term in vivo application. PHEMA only partially reduces non-specific protein adsorption. Other existing anti-fouling materials give rise to foreign body reactions. Therefore, it is important to develop a novel anti-fouling material that would tackle these problems.
Zwitterionic polymers are polyampholytes bearing equivalent cationic and anionic charges on the same repeating unit. Over the past decade, such polymers have attracted considerable attention due to the outstanding anti-fouling properties attributed to their strong interaction with water via ionic solvation (in contrast to that of polyethylene glycol, which relies on hydrogen bonding to bind water), ease of functionalization, and design flexibility. Polycarboxybetaine, polysulfobetaine and poly(methacryloyloxyethyl phosphorylcholine) are three types of zwitterionic materials that have been most widely investigated. One of the major challenges for biomaterials is to maintain a controllable bio-interface, promote specific binding and resist non-specific binding of protein and cells, thus minimizing biofouling and potential infections. New biomaterials are urgently needed to address the intrinsic drawbacks such as poor mechanical property, degradability and biocompatibility.
Accordingly, there is a need for a hydrogel material that addresses or alleviates one or more disadvantages mentioned above. There is a need to provide a hydrogel material having desirable properties.